The shortcomings of traditional mechanical couples and gears are often overlooked since they are ubiquitous and frequently represent the only means of getting the right torque and rotation speed from, as an example, a motor to a propeller shaft. Gear teeth run into and rub against one another. This wastes energy, generates heat, emits vibration and sound, generates abrasive particles, wears gear teeth, makes lubrication essential, limits the service life of gears, and necessitates maintenance. In addition, incorporating fluid flow, maintenance access and heat transfer characteristics increases the complexity and cost of gears and transmissions. A gear that operated with interlocking magnetic fields, on the other hand, would not require physical contact between teeth. Despite a long list of potential advantages, magnetic couples and gears have heretofore been extremely limited in their application by their low torque densities (i.e., torque per volume of couple or gear mechanism). Higher torque densities would translate directly into broader applications for magnetic gears and couples.